The present invention relates generally to the field of coatings for various substrates, including carbon-carbon composite (CCC). In some embodiments, the invention relates to coatings comprising trilayers of ZnO/Al2O3/ZrO2.
Carbon-carbon composite (CCC), a well-recognized aerospace structural material, is known for its high-temperature strength and low relative density. For example, jet engine manufacturers use composite variable stator vane bushings, such as CCC, in commercial and military jet engines. Conventional pure (untreated) CCC exhibits fretting wear after a certain amount of operational use and subsequently must be replaced at a significant cost.
Fretting (oscillatory) wear of pure (uncoated) CCC limits its lifetime in applications, such as bushings used in jet engine blisks (blade integrated disks), which are compressor impellers with integrated blading for commercial and military jet engines. Commercial, porous CCC bushings still require replacement as part of routine scheduled-based maintenance by jet engine manufacturers.